Measuring system

Abstract: A monitoring system 10 having a stylus 16 mounted to a support 110 that controllably moves the stylus along a travel path as it contacts an object of interest 12. The object is supported by a rotating turntable 30 and held in place by a manually actuatable retainer 36 that exerts a repeatable downward force on the object. A frame 110 that supports the stylus is supported by a flexure plate that makes the task of orienting the frame easier. The frame supports a saddle that can be raised and lowered by a belt system driven by a D.C. pancake motor. The entire monitoring system achieves a required degree of accuracy in monitoring object shape at a reduced manufacturing cost.

Description: The present invention concerns an automated monitoring system for determining or confirming the shape of a machined item such as a gear. The present applicant, M&M Precision Systems Corporation, has commercialized prior monitoring systems for determining or confirming the shape of a machined item such as a gear and the like. These prior art monitoring systems are commercially sold under the designation Model Numbers 3012, 3018, 3025, 3040 and 3060 where the last two digits indicate the diameter of the workpieces (in inches) the system is capable of monitoring. The prior art systems sold by the Assignee of the invention include a moveable frame mounted to a base and including a drive system for moving a stylus or probe along three independent directions by controlled energization of multiple drive motors. As an example, the frame could be moved horizontally in the direction of a first axis by means of a motor that rotates a precision ground ballscrew. As the ballscrew rotates the frame is moved very accurately with respect to an origin. The carriage supports an arm extending away from the frame having a stylus at one end which comes into contact with the object under examination. The stylus is constructed using an LVDT monitoring probe. Such a probe produces an output signal related to the position of a moveable probe member with respect to the probe body. Through a controlled monitoring of the output signals from the probe, and controlled continuous movement of the frame, including a feedback monitoring of optical encoder signals as the frame moves, the monitoring system can accurately determine the position of the moveable probe tip. This allows the monitoring system to accurately compare any curve on a surface of a machined part with the desired shape of that surface. Alternately the monitoring system can test an unknown surface and store a representation of the part for later use as a standard. In accordance with the prior art monitoring systems, the object under examination is supported on a turntable and held in place by a clamping member having a live center which is motor actuated. The object under examination is placed on the turntable and the clamp energized to bring the object engaging portion of the clamp into engagement with the object. Once the object has been secured to the turntable, controlled energization of a turntable drive causes the object to rotate. Precise control over the turntable rotation is achieved by means of an air bearing which supports the turntable above a turntable support and feedback monitoring of sensed turntable rotation. The combination of extremely accurate rotation of the object under examination, in conjunction with the use of a ballscrew drive for moving the carriage has to the cost of making prior art monitoring systems. Accurate movement and position sensing require the frame that supports the probe to be leveled both during manufacture of the monitoring system and as it is installed. This is achieved in the prior art (see e.g. US-A-4790078) by scraping engagement surfaces of the carriage support during fabrication of the monitoring system. This scraping process is done manually and performed on a trial-and-error basis. A significant amount of time during production of a monitoring system goes into the scraping and leveling of the moveable carriage that supports the probe or stylus. The prior art systems sold by M&M Precision Systems are expensive to build. It is one object of the present invention to provide an accurate yet economic monitoring system without resort to some of the more expensive components and techniques used in prior art monitoring systems. The invention provides a monitoring system comprising: a stylus mounted to a support that can be moved along a controlled travel path as the stylus contacts an object; a base having a generally level support surface; track means supported by the base to define a travel path for a movable frame and attached stylus; a movable frame mountable on the track means, the frame having an arm that extends away from said frame and supports the stylus to orient the stylus relative to the base; and frame support means comprising a flexure plate connected to the base by means of multiple spaced connectors which can be loosened and tightened for orienting the frame relative to the base during set up of the monitoring system. Preferably there is an object support for securing an object to be examined in a position relative to the frame, said object support comprising a column including a magnetic portion and a movable object retaining member supported by the column and including a magnet for fixing the object retaining member relative the column. The object support may further comprise a turntable, a motor for turning the turntable, and a turntable support comprising a precisely ground bearing coupled to the motor for rotating the turntable. The object support may comprise spaced apart object contacting members, one contacting member coupled to the turntable and a second object contacting member connected to the movable object retaining member. The movable object retaining member may comprise a base and a bearing for supporting said second object contacting member relative to the base. The movable object retaining member preferably further comprises rotation limiting means for limiting rotation of the second object contacting member until the object retaining member is fixed with respect to the column. The frame may comprise spaced apart upright columns supporting a probe support having track means for moving the probe support in a direction orthogonal to movement of the frame and further comprising a belt drive for moving the probe support along the orthogonal direction. The frame may comprise a guide for supporting a vertically movable probe support, a driven pulley coupled to said guide at one end and an idle pulley coupled at an opposite end of said guide, and a first belt that engages the driven and idle pulleys and connects to the movable probe support to move the probe support up and down. Preferably a second belt that overlies the first belt and holds the probe support in the event the first belt breaks. Preferably the system comprises an object support for securing an object to be examined in a position relative the frame, said object support comprising an upright that supports a movable object retainer and means operable to raise and lower the object retainer relative an object to secure the object. Preferably, a pneumatic actuator means operable to raise and lower the object retainer is provided. The object retainer is preferably supported by a bearing to allow rotation of the retainer about the vertical axis except while the object retainer is moving up or down. The upright preferably has an exposed ferro-magnetic surface and the retainer has a magnet which is moved toward the ferro-magnetic surface to lock the retainer in position while freeing the retainer for rotation. The object retainer preferable comprises: i) a rotatable center for contacting the object after the object is placed on the turntable; ii) a support for the rotatable center that can be raised and lowered relative the turntable to hold the object between the turntable and the center; and iii) a user-operated actuator for raising and lowering the support having a pneumatically operated cylinder and piston attached to the support for the rotatable center. A monitoring system constructed in accordance with the present invention includes a stylus mounted to a support that can be moved along a controlled travel path as the stylus engages an object. The monitoring system described below includes a base having a generally level support surface for mounting a frame for movement along a travel path. The frame includes an arm that extends outwardly away from the frame and supports a stylus which can be positioned relative the base by controlled movement of the frame. A track is supported by the base and defines a travel path for the frame and attached stylus. The carriage support includes a flexure plate connected to the base by means of multiple connectors which can be adjusted to level the carriage and orient it in a preferred orientation during setup of the monitoring system. Use of a flexure plate rather than controlled scraping of engagement surfaces is a significant factor in reducing the cost of producing a monitoring system in accordance with the invention. By an alignment process of adjusting the connectors between the flexure plate and the base, the setup of the monitoring system is simplified both at the factory as the monitoring system is being produced as well as on site where the monitoring system needs periodic adjustment during its operation. The object support includes a column and an object retainer mounted to the column that moves along a linear travel path. The object retainer is moved with the help of a gas activated drive, thus eliminating the expensive ballscrew drive mechanism used in the prior art. The user places the object onto a turntable and manually adjusts the position of the object retainer to secure the object in place prior to automated monitoring of the object's shape. The moveable frame supports a so-called saddle which supports the stylus or probe for up and down movement. A linear guide or track supports the saddle for such movement. A belt drive system reeved over a drive pulley and idler pulley engage the saddle for moving the saddle up and down relative the carriage. The drive system preferably incorporates a so-called pancake motor, named for its flat shape and compact configuration. The so-called pancake motor is a DC motor which can be energized by a control system to move the saddle relative the carriage. The belt system replaces the more costly ballscrew used in the prior art. To eliminate damage of the monitoring system if the belt breaks, a duplicate belt not under tension, is also attached to the saddle. If the primary or tensioned belt breaks, the secondary belt will prevent the carriage from falling. The expensive air bearing system of the object turntable has been replaced with a precision ground bearing for supporting the turntable. A second pancake motor coupled to the turntable rotates the object as the stylus or contact probe comes into contact with the object. One embodiment of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a monitoring system constructed in accordance with the present invention; Figure 2 is an enlarged perspective view of the Figure 1 monitoring system showing an object holder for securing an object in place on a rotating turntable in spaced relation to a moveable stylus; Figure 3 is a plan view of a stylus support for moving the stylus into engagement with an object held in place on the rotating turntable; Figure 4 is an elevation view of the object holder for securing an object on the rotating pedestal; Figure 5 is a partially sectioned view of the object holder for locking an object in place; Figure 5A is a partially sectioned view of the object holder before it locks the object in place; Figure 5B is an enlarged view showing a top portion of a rotatable center that forms part of the object holder; Figure 6 is a plan view of the object holder of Figures 4 and 5; Figure 7 is a section view of a motor and bearing supporting a precision spindle for controllably rotating an object secured to the spindle by the object holder; Figure 8 is a plan view of the object spindle; Figure 9 is an elevation view of a base that supports a moveable frame to which the stylus or probe is attached; Figure 10 is a view from the plane 10-10 defined in Figure 9; Figure 11 is a plan view of a frame that is mounted to the base shown in Figure 9 for linear translation along a travel path to provide one direction of movement for the stylus; Figure 12 is a view of the frame as seen from the plane 12-12 in Figure 11; Figure 13 is a view of the frame as seen form the plane 13-13 in Figure 12; Figure 14 is a side elevation view of a saddle mounted to the carriage depicted in Figures 11-13; Figure 15 is a view as seen form the plane 15-15 in Figure 14; Figure 16 is a view as seen form the plane 16-16 in Figure 15; Figure 17 is an elevation view of an alternate and presently preferred object holder for securing an object on a turntable; Figure 18 is a side elevation view of the alternate object holder of Figure 17 as seen from the plane defined by the line 18-18; Figure 19 is a plan view of the Figure 17 object holder with a panel removed; Figure 19A is an enlarged plan view showing a coupling between the object holder and a pneumatic drive for moving the holder; Figure 20 is a section view as seen from the plane defined by the line 20-20 of Figure 17; Figure 21 is an elevation view of a circuit board supporting a battery for energizing light-emitting diodes for signaling the position of the retainer; Figure 21A is an enlarged view showing an actuator for energizing the light-emitting diodes; Figure 22 is an elevation view as seen from the plane 22-22 of Figure 21; Figure 23 is an enlarged elevation view of a probe support; and Figure 24 is a partially sectioned of the Figure 23 probe support. Figure 1 is a perspective view of a monitoring system 10 that is used to evaluate a workpiece 12 such as a machined product that has been manufactured to certain specifications. The particular workpiece 12 depicted in the drawings is a gear have a tooth pattern that is to be checked by the monitoring system 10. One use of the monitoring system is to perform a periodic check of the workpieces that are being produced and determine if the workpiece falls within customer specifications. An alternate use of the monitoring system is for checking the shape of an unknown curve and defining that curve with a series of co-ordinate locations. Either of these applications typically requires that the workpiece be rotated about a center axis 14 as a probe or stylus 16 contacts a surface of the workpiece. The particular gear shown in the drawings requires that the probe 16 contact an outer surface but the probe can be configured to also monitor the shape of an interior curve of a annular object. The gear shown in Figures 1 and 2 is mounted to a rotating circular table 30 supported on a base 32. Extending upward away from the base 32 is a column 34 that supports an object retainer 36. Prior to monitoring the shape of an object, the object must be positioned in contact with the table and fixed in place by the object retainer 36 by moving the retainer up and down with respect to the column 34. While in the prior art the step of fixing the workpiece to the table was automated by a motor and a ballscrew the disclosed monitoring system 10 employs a manually operated object retainer 36. Once the workpiece has been fixed to the table 30 the stylus 16 is brought into engagement with a surface of the workpiece and the table is rotated as the stylus moves in and out to follow the contour of the workpiece. In a use where the monitoring system is to monitor a shape and compare that shape with a known standard the stylus is made to follow a controlled path and deviations between the sensed shape of the object and the controlled path are plotted. The monitoring system includes an operator console 50 which allows an operator or user to view the monitoring process on a viewing screen 52. The viewing screen is updated by a computer 54 that responds to user inputs entered at a keyboard 56 and responds to those inputs to display data and perform calculations. The computer rests on a base 58 spaced to the side of base 32 supporting the moving stylus 16. In accordance with a preferred embodiment of the invention the monitoring system 10 includes a second programmable controller (not shown) to control movement of the stylus 16. The second programmable controller has an interface that is electrically coupled to sensors and servo drives that monitor and control movement of the stylus 16. The second controller also communicates with the computer 54 via a serial interface. The base 32 positioned beside the console 50 supports structure for moving the stylus along a controlled travel path. The base 32 defines a generally flat, level surface 102 (Figure 2) that supports a moveable frame 110. A frame guide includes two spaced apart fixed rails 112, 114 (Figure 10) attached on opposite sides of a opening 116 in the base 32. The rails 112, 114 constrain the frame 110 to a linear travel path that defines a Y-direction in an orthogonal co-ordinate system. Since the frame 110 moves back and forth in the Y-direction, the frame is sometimes referred to as the Y-saddle. The frame 110 includes a frame base 120 (Figures 10,12) which is a flat metal plate positioned within the opening in the base 32. Two rails 122, 124 extend down from a bottom surface of the base 120 between the rails 112, 114 that are attached to the base 32. The two rails 112, 122 face each other and are connected to a retainer 126 that traps ball bearings between two retainer strips having a ball channel machined along their length. A second retainer 128 is connected to the rails 114, 124 and has two retainer strips having a ball channel. Ball bearings within the two retainers 126, 128 rotate as the frame 110 moves relative to the base 32. A motor 140 is connected to the base 32 by means of a motor mount 142. This motor is a so-called pancake motor due to its physical appearance. It is a D.C. servo motor commercially available from Infranor Inc. of Naugatuck Conn. under part numbers MT80, MT300 and MT4500. The motor has an output shaft 144 that rotates in response to controlled actuation of the motor by a monitoring system controller. The shaft 144 rotates a drive pulley 146 supported by a support bearing 148. Reeved over the pulley 146 and an idle pulley 150 supported on an opposite side of the base 32 is a drive belt 152. The belt 152 is pinned to an underside of the frame base 120 by connectors 154 that pass through the belt 152 so that controlled rotation of the output shaft from the motor 140 results in linear movement of the frame 110. In accordance with a preferred embodiment of the invention the belt 152 is constructed from a strong yet lightweight steel having a thickness of about 0.13mm (0.005 inches). As the motor moves the frame 110 relative to the base 32 along the "y" axis, this movement is monitored by an optical encoder 160 that monitors movement of the frame 110. The encoder includes an optical sensor mounted to the base 32 and the frame supports a linear scale that moves back and forth relative the optical sensor. While the motor shaft can be very accurately actuated to move the frame, the position of the frame in the "y" direction is determined based upon outputs from the encoder 160. Orienting the Frame The orthogonality of all axes of movement of the frame 110 with respect to each other is critical to the performance of the monitoring system 10. Rather than use the scraping process of the prior art, the disclosed monitoring system uses flexure plates to adjust the orthogonality. Interposed between the frame base 120 and the frame 110 is a about 19mm (3/4 inch) thick steel flexure plate 162 (Figure 12) that is attached to the base 120 by means of threaded connectors 164 spaced in a triangular pattern that extend down through the plate 162 and into threaded openings 165 in the base 120. The connectors are preferably socket bolts seated within circular sockets in the plate 162. Two connectors 164a,164b are spaced to form a line that intersects the "y" axis at a right angle. The third connector 164c is spaced along the "y" direction from the other two connectors 164a,164b and located midway between these two in an "x" direction. After the frame base 120 is attached to the monitoring system base 32, the flexure plate is connected to the frame 110 and then the flexure plate 162 is attached to the moveable base 120. As the plate 162 is being attached the orientation of the frame relative to the base 32 is adjusted by tightening or loosening the connectors 164. By adjusting the connectors the orthogonality of the frame 110 with respect to the base 32 is adjusted. The frame 110 supports a "z" saddle 200 (Figure 13) for up and down movement with respect to the base 32. Vertically oriented frame supports 210, 212 extend upward from the flexure plate 162 and define a linear travel path for the saddle 200. Rails 214, 216 attached to the supports 210, 212 carry a ball bearing retainer 220 that is also connected to rails 222, 224 coupled to the saddle 200 by connectors 225 that extend through the saddle 200. As the saddle 200 moves up and down with respect to the supports 210, 212, ball bearings trapped within the retainer 220 rotate and allow the relative translation between the frame 110 and the saddle 200. A second pancake motor 230 is attached to the frame 110 by means of a bracket 232. An output shaft 234 of the motor rotates a drive pulley 236. A two layer z-axis drive belt 240 is reeved over the drive pulley 236 and an idle pulley 242 attached a base 244 of the frame 110. Z-axis belt drive The saddle 200 supports a bracket 250 connected to the saddle and the double layer belt 240. Connectors pass through a hole in both layers of the double layer belt 240 into the bracket 250 to secure the saddle 200 to the belt 240. Controlled energization of the motor 230 raises and lowers the saddle 200 by applying movement to the belt 240. A primary belt is under tension. In the event this primary belt breaks, a secondary belt that overlies the primary belt will prevent the saddle from falling and possibly damaging the monitoring system. Both belt layers are constructed from a thin steel layer 0,13 mm (0.005 inches) thick. Use of a double layer drive belt 240 is less expensive to manufacture than the ballscrew drive of the assignee's prior art systems. This and use of the pancake motor 230 provides controlled precise movement of the saddle 200 and at a significantly lower cost. Up and down movement of the "z"-saddle 200 is monitored by a linear encoder 252 that senses motion and positioning of the saddle 200. The encoder sends back signals corresponding to movement of the saddle 200 that are used by the programmable controller to determine the position of the stylus 16 relative to a reference position. Mounted to the z-saddle 200 is a probe support base 260 (Figs 14-16). This base supports a saddle 270 for side to side movement in the "x" direction in response to controlled energization of a motor 262. The "z" saddle 200 has an outer surface 201 (Figure 12) that is generally parallel to the x-y plane as that plane is defined in the drawings. The surface 201 supports the base 260 by means of connectors that are threaded into openings 203 in the surface 201. The x-saddle 270 is mounted for back and forth movement in the x direction by means of a track that includes rails 274, 276 fixed to the saddle and a rail 278 coupled to the probe support 260. These rails support a retainer having ball bearings 280 that rotate as the rails move relative to each other in response to actuation of the motor 262. Attached to the base 260 by means of suitable bearings are drive and idle pulleys 282,284 that support a drive belt 286 attached to the saddle 270 by connectors which connect the belt to two brackets 288. A linear encoder 290 monitors the x-direction movement of the saddle 270 thereby allowing the monitoring system controller to determine the x co-ordinate position of the stylus 16. A probe arm 292 (Fig. 3) is mounted to a probe mounting block 294 coupled to the saddle 270. The orientation of the probe arm 292 can be adjusted depending on the object under examination by the monitoring system. Such probe arms are known in the prior art and are incorporated, for example, in the assignee's prior art monitoring systems. During setup of the monitoring system 10 the three motors 140, 230, 262 are manually actuated by an operator by means of a touch panel control 300 on the front of the base 32. The control panel allows the operator to bring the stylus 16 into contact with a reference object 302 whose position on the base 32 is known. By engaging surfaces of the reference object 302 the monitoring system defines a home position. As the probe or stylus moves away from this home position the controller updates the position of the stylus. Thus, as the monitoring system moves the stylus 16 along a controlled path with respect to the home position corresponding to the desired object's shape, the controller knows the x, y, z co-ordinate of the path and can compare deviations from the path that are sensed by the stylus. Manually operated Object retainer 36 During a typical examination of an object of interest such as a gear or the like, the monitoring system 10 controls the rotation of the object on the rotating turntable 30. The object to be examined is held in place on the turntable 30 by an upwardly extending conical support 310 (Fig 7) that is coupled to and rotates with the turntable and supports a bottom of the object 12. A center 312 aligned with the axis 14 and having a downwardly extending conical portion 313 engages a top portion of the object. To mount the object on the turntable 30 an operator lifts the retainer 36 out of the way and places the object on the support 310. The retainer 36 is then manually pulled down until the center's conical end 313 contacts the object and the retainer 36 is locked in position by rotating a locking lever 320. Details of the retainer 36 are shown in Figures 4-6. The retainer is constrained for up and down movement with respect to the upright 34. The upright 34 includes a post 322 having a ferromagnetic surface 324 along its length. The surface 324 is spaced from a magnetic base 326 that is supported above a retainer base 328 connected to the post 322 by means of a linear bearing commercially available from THK corporation of Japan. With the lever 320 in an unlocked position (clockwise as seen from above in Fig. 6) the base 328 can be raised and lowered to position the retainer. The base 328 is partially supported by two air cylinders 330, 332 that ease the raising and lowering of the retainer 36. When the lever 320 is locked the retainer 36 is fixed in its "z" position. The magnetic base includes a magnet.within a housing. When the lever 320 is rotated from its unlocked to locked position in a counterclockwise sense, the magnet rotates within the base housing and a magnet pole moves toward the column surface 324 to increase the magnetic attraction between the magnet and the ferromagnetic surface 324. This locks the retainer 36 in its "z" position. A preferred magnetic base is commercially available from Traverse Tool Inc. With the lever 320 in its unlocked position (See Fig. 5A) the center 312 is locked and does not rotate. When the lever locks the retainer in the z position, it also frees the center 312 to rotate with respect to the base 328 and applies a repeatable downward force on the retainer 36 to apply a securing force onto the object to be examined thereby eliminating operator induced errors. Near an end of the counterclockwise travel of the lever 320 the lever contacts a curved head of a pin 330 threaded along a length of its opposite end. The pin threads into an opening 332 in the base 328 and as the lever 320 is rotated to the locked position (shown in Figure 5) the pin 330 is forced downward and this downward force is transmitted to the base 328. The base 328 moves downward with respect to the magnet base 326 and loads a thrust bearing 340 (Fig. 5B) supported by the base. A preferred thrust bearing is commercially available from Winfred M. Berg Inc. of East Rockaway, N.Y. When the thrust bearing 340 is loaded the center 312 rotates in a bearing 342 so that the object 12 trapped between the center 312 and the conical support 310 on the turntable 30 can be rotated. A spring 344 contacts a enlarged head 346 at the top of the center 312. This spring 344 is trapped against the thrust bearing 340 within a circular depression 346a in the head 346 and exerts a repeatable downward force against the center 312 (and hence the object) as the lever fixes the retainer to the support 34. An alternate and presently preferred manually operated object retainer 36' is depicted in Figures 17-22. This retainer 36' is fixed to an upright 400 along an elongated track 402 that extends verticallly along the upright. As in the earlier described embodiment, the retainer 36' supports a center 312 aligned with an axis of rotation of the turntable 30 having a downwardly extending conical portion 313 that engages the top portion of the object under examination. To mount the object onto the turntable, an operator moves the retainer 36' upward and places an object such as a gear on the support 310. The retainer 36' is then moved down until the center's conical end 313 contacts the object and an indicator light signals the user the object is fixed in place. As seen most clearly in the section view of Figure 20, the center 312 is mounted for rotation within a bearing 404 supported by a retainer base 406. The base 406 is attached to a bearing housing 408 (Figure 18) that encloses a recirculating bearing that allows the housing to move smoothly up and down the track 402. A preferred combination bearing and track is commercially available from THK under Part No. HRW 50CA. As the conical end 313 contacts the object under examination, further downward movement of the retainer 36' applies an upward force against the center 312. A thrust bearing 340 (Figure 20) such as the thrust bearing shown in Figure 5B above, is loaded by a force of the compression spring 344 trapped against one surface of the thrust bearing and contained by a collar 412 attached to the base 406. Upward movement of the center 312 loads the thrust bearing and allows the center 312 to rotate. A pin 414 attached to the center 312 extends upwardly above the center through the spring 344. As the center loads the bearing 340, the pin 414 moves upward and engages a bottom surface of a conductor 422 that is supported by a printed circuit board 420 attached to the collar 412. The pin 414 and center 312 are grounded through the base 406. When the pin 414 engages the conductor 422, a circuit is completed through an LED 432 and battery 426 supported within a housing battery 428. An output from the LED 432 is visible through slot 425 in a cover 427 that overlies the circuit board 420. Further movement of the pin 414 flexes the conductor 422 and causes it to contact a second conductor 424 to light a second light-emitting diode 430 mounted to the retainer 36'. The light-emitting diode 432 is green and indicates to the user that a specified load has been applied to the object under examination, and examination can begin. If the user inadvertently causes the center to exert too strong a downward force against the object, the second light-emitting diode 430 will be illuminated indicating the user should back off the position of the retainer 36'. Conductive paths (not shown) on the circuit board 420 connect the two LEDs 432, 430 in parallel with the battery 426 when the conductors 422, 424 touch. Up and down movement of the retainer 36' is accomplished by means of a height adjustment system 440 which supports the retainer 36' and positions the retainer 36' in response to rotational adjustment of a handle 442 at the front of the apparatus. Clockwise rotation of the handle 442 causes upward movement of the retainer 36'. Counterclockwise rotation of the handle causes the retainer 36' to move downward. As the retainer is lowered by means of counterclockwise rotation of the handle, the center 312 contacts the part under examination and the aforementioned loading of the thrust bearing allows the center to rotate. Further downward movement of the retainer 36' causes the green and red lights to be actuated. In the event the red light is actuated, the user can rotate the handle in a clockwise rotation to lift the retainer 36' so that an appropriate force traps the object under examination between the center and the rotating pedestal. The preferred height adjustment system 440 is sold under the designation MOVOTEC® by Suspa Inc. of Grand Rapids, Michigan. An elongated body 444 attached to the base 32 supports the handle 442 and directs pressurized fluid through a flexible conduit 446 attached to a vertically oriented elongated tube 448 that supports a moveable piston 450. As seen in the enlarged view of Figure 19A, one end of the piston 450 is attached to a bracket 452 connected to the retainer base 406 by connectors 454. As the system operator rotates the handle clockwise and counter clockwise, the movement of the piston raises and lowers the retainer 36'. Rotatable Turntable 30 The object turntable 30 is rotated about the axis 14 by a pancake motor 350 supported by a turntable base 352 fixed to the base 32. (See figures 7 and 8) The motor 350 has an output shaft 354 connected by a transmission 356 to a rotating hub 358 that is attached to the turntable 30 by means of threaded connectors 360. The hub 358 and turntable 30 are supported by a matched set of angular contact bearings 370,372 commercially available from Barden under part number 15HDL having a advertised maximum radial runout of 3,8 µm (0,00015 inches). The bearings have inner races 370a,372a and outer races 370b,372b. The outer race 372b rests against an annular lip 373 in the base 352 and the inner race 372a is supported by an inner race seat 374 connected to the hub. An inner face 375 of the turntable 30 rests against the inner race 370a and an annular plate 376 is coupled to the base 352 and rests against the outer race 370b. The components that engage the bearings 370,372 and therefore support the turntable 30 are machined to extremely tight tolerances. By carefully machining these components to these tolerances, the radial and axial runout of the turntable is reduced from the bearing manufacture's advertised specifications to less than 0,5 µm (0,0002 inches) axial and radial runout. This is approximately an order of magnitude better than the bearing manufacturer's advertized tolerance. An inductosyn feedback device have a rotor 380 and a stator 382 also monitors the rotation of the turntable 30 and in combination with the precise bearing support of the turntable allows the rotation of the object to be precisely controlled by means of the programmable controller. Figures 23 and 24 illustrate the means of attaching the probe arm 292 to the x-saddle 270. The position of the probe arm 292 relative to the x-saddle 270 can be adjusted to bring the probe 16 to a position so that controlled activation of the pancake motors precisely positions the probe 16. Once the probe arm 292 is fixed relative the xyz coordinate system, and the probe 16 is moved into contact with sides of the object 12 so that the controller knows the coordinates of the probe 16 with great precision. To roughly position the arm relative the x-saddle, the user must free the probe arm 292 for back and forth movement along the x direction. A knurled knob 460 is rotated to loosen the probe arm 292. The probe 292 is supported by a bracket 462 and housing 294. Extending through the bracket 462 is a pin 466 that rotates as the knurled knob 460 is rotated. A clutched fastener is loaded by rotation of the knurled knob 460. As the knob is rotated, the fastener causes the bracket 462 to pivot slightly about a pivot point 464 in a clockwise direction as seen in Figure 24. This tightens the engagement between the bracket 464, housing 294, and the probe arm 292. Overtightening of the bracket 462 against the probe arm 292 is prevented by the clutched fastener. As the user continues to rotate the knurled knob, the clutch prevents the fastener from overtightening and thereby avoids stresses on the probe arm that affect accuracy of the probe measurements. The present invention has been described with a degree of particularity. It is the intent that the invention include all modifications and alterations from the disclosed design falling within the scope of the appended claims.

Claims: A monitoring system (10) comprising a stylus (16) mounted to a support (110) that can be moved along a controlled travel path as the stylus (16) contacts an object (12), and comprising: a base (32) having a generally level support surface (102); track means (112,114) supported by the base (32) to define a travel path for a movable frame (110) and attached stylus (16); a movable frame (110) mountable on the track means (112,114), the frame (110) having an arm that extends away from said frame and supports the stylus to orient the stylus relative to the base; and characterised by frame support means comprising a flexure plate (162) connected to the base (32) by means of multiple spaced connectors (164) which can be loosened and tightened for orienting the frame (110) relative to the base (32) during set up of the monitoring system (10). A monitoring system according to claim 1, further characterised by an object support for securing an object (12) to be examined in a position relative to the frame (110), said object support comprising a column (34) including a magnetic portion (324) and a movable object retaining member (36) supported by the column (34) and including a magnet (326) for fixing the object retaining member (36) relative the column (34). A monitoring system according to claim 2 wherein the object support further comprises a turntable (30), a motor (350) for turning the turntable (30), and a turntable support (358) comprising a precisely ground bearing (370,372) coupled to the motor (350) for rotating the turntable (30). A monitoring system according to claim 3, characterised in that the object support comprises spaced apart object contacting members, one contacting member (310) coupled to the turntable (30) and a second object contacting member (313) connected to the movable object retaining member (36). A monitoring system according to claim 4, characterised in that the movable object retaining member (36) comprises a base (328) and a bearing (340) for supporting said second object contacting member (313) relative to the base. A monitoring system according to claim 4 or 5, characterised in that the movable object retaining member (36) further comprises rotation limiting means for limiting rotation of the second object contacting member (313) until the object retaining member (36) is fixed with respect to the column. A monitoring system according to any of claims 1 to 6, characterised in that the frame (110) comprises spaced apart upright columns (210,212) supporting a probe support (200) and having track means (214,216) for moving the probe support (200) in a direction orthogonal to movement of the frame (110) and further comprising a belt drive (240) for moving the probe support (200) along the orthogonal direction. A monitoring system according to any preceding claim, characterised in that the frame (110) comprises a guide for supporting a vertically movable probe support (200), a driven pulley (236) coupled to said guide at one end and an idle pulley (242) coupled at an opposite end of said guide, and a first belt (240) that engages the driven (236) and idle (242) pulleys and connects to the movable probe support (200) to move the probe support (200) up and down. A monitoring system according to claim 8, further characterised by a second belt that overlies the first belt (240) and holds the probe support (200) in the event the first belt breaks. A monitoring system according to any preceding claim, further characterised by an object support for securing an object (12) to be examined in a position relative the frame (110), said object support comprising an upright (34) that supports a movable object retainer (36) and means (330,332) operable to raise and lower the object retainer (36) relative to an object (12) to secure the object (12). A monitoring system according to claim 10, comprising means (320) operable to move the object retainer (36) into engagement with the object (12) and to fix a base (328) of the object retainer (36) in place relative to the upright (34) while maintaining a downward force of engagement between the object retainer (36) and the object (12). A monitoring system according to claim 10 or 11, characterised in that the object retainer (36) is supported by a bearing (340) to allow rotation of the retainer (36) about the vertical axis except while the object retainer (36) is moving up or down. A monitoring system according to claim 12, characterised in that the upright (34) has an exposed ferro-magnetic surface (324) and the retainer (36) has a magnet (326) which is moved toward the ferro-magnetic surface (324) to lock the retainer (36) in position while freeing the retainer (36) for rotation. A monitoring system according to any of claims 10 to 13, characterised by pneumatic actuator (330,332) means operable to raise and lower the object retainer (36). A monitoring system according to claim 14, characterised in that the object retainer (36) comprises: i) a rotatable centre (313) for contacting an object (12) after the object (12) is placed on a turntable (30); ii) a support (36) for the rotatable centre (313) that can be raised and lowered relative to the turntable (30) to hold the object (12) between the turntable (30) and the centre (313); and iii) a user-operated actuator for raising and lowering the support and having a pneumatically operated cylinder and piston (330,332) attached to the support (36) for the rotatable centre (313).

Inventors: DENISON CHARLES W JR, EVANS MICHAEL, LOMBARDO MICHAEL A, PARKER MICHAEL A, ULLERY STEVEN, DENISON, CHARLES W., JR., EVANS, MICHAEL, LOMBARDO, MICHAEL A., PARKER, MICHAEL A., ULLERY, STEVEN
Applicants: M & M PRECISION SYSTEMS CORP, M & M PRECISION SYSTEMS CORPORATION
Application year: 1994
Main classification: G01B5
IPC codes: G01B21, G01B5